GHSA-mwqm-4fw3-cjvr
symfony/ux-autocomplete: XSS via unescaped AJAX response data
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Packagist | symfony/ux-autocomplete | >= 2.2.0, < 2.36.0 | 2.36.0 |
| Packagist | symfony/ux-autocomplete | >= 3.0.0, < 3.1.0 | 3.1.0 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Description
The Stimulus controller shipped with `symfony/ux-autocomplete` renders AJAX response items into the dropdown by interpolating the `text` field directly into HTML template literals (`<div>${item[labelField]}</div>`) inside `_createAutocompleteWithRemoteData()`. The value is parsed as HTML rather than text, so any markup contained in the AJAX response is executed by the browser.
When the dropdown values are derived from user-supplied content, an attacker can craft a string that triggers stored XSS in the browser of any other user who later opens a page containing an autocomplete widget backed by the same data.
### Resolution
The `option` and `item` renderers used in `_createAutocompleteWithRemoteData()` now use TomSelect's `escape` helper to HTML-escape the value by default. Endpoints that legitimately return HTML (for example, to highlight the search term) can opt back in to the previous behavior by setting `options_as_html: true`. The `AutocompleteChoiceTypeExtension` normalizer that previously forced `options_as_html=false` when `autocomplete_url` was set has been dropped so the opt-in is reachable from the form layer.
The patch for this issue is available [here](https://github.com/symfony/ux/commit/842ae54bc74de389299f975f01aafae272cb0019) for branch 2.x (and forward-ported to 3.x).
### Credits
Symfony would like to thank Alex Ashkov for reporting the issue and Hugo Alliaume for providing the fix.
References
External links from the advisory. They lead to third-party sites.